The present disclosure relates to an imaging device, an image signal processing method, and a program that conduct a dynamic range extension process and a noise removal process, for example.
In an imaging device of the related art, a dynamic range extension process and a noise removal process are each conducted separately. Herein, a dynamic range extension process refers to a process that extends the dynamic range of a recorded image signal by mixing recorded image signals corresponding to the images of multiple frames recorded with different exposure times. Meanwhile, a noise removal process refers to a process that removes noise imposed onto respective images by mixing recorded image signals recorded consecutively in the time direction.
Japanese Unexamined Patent Application Publication No. 2010-41200 discloses an example of conducting a dynamic range extension process by conducting a mixing process on image signals corresponding to the images of two frames recorded with different exposure times. With this process, a noise removal process is conducted by using a frame recursion quantity, which depends on motion determination results and exposure times, to conduct a mixing process and a blending process on the mixed image signal of the previous frame and the mixed image signal of the current frame.
Japanese Unexamined Patent Application Publication No. 2008-160881 discloses technology that uses timewise consecutive image signals with the same exposure times with respect to image signals corresponding to the images of multiple frames recorded with the same or different exposure times. Noise is then removed from the image signals by conducting a finite impulse response (FIR) process. Furthermore, dynamic range extension is conducted by mixing image signals with different exposure times and with noise removed. Japanese Unexamined Patent Application Publication No. 2008-160881 discusses FIR. However, it is also conceivable to conduct image mixing in order to extend dynamic range after conducting an infinite impulse response (IIR) process on each timewise consecutive exposure time.